The invention concerns a circuit arrangement for compensating for the crosstalk occurring between adjacent cells of a linear photodiode array in a scanner for an illuminated object. Scanners of the type addressed by this invention are generally described in U.S. Pat. Nos. 3,800,078 and 3,800,079. The object to be scanned is illuminated at 45.degree. by means of a light guide positioned in front of the optical system. Part of the light guide bundle is used for the intensity control of the light source. The radiation reflected off the object to be scanned is detected by a self-scanning photodiode array in integrated circuit technology, with each photodiode supplying a densitometric image of the scanned surface. For scanning such an object, the photodiode array in a scanning head is led in the X- and the Y-direction across the object. The signals derived from the photodiode array have to be subjected to several operations before they can be processed further in a data processing system. Two of these operations are known from the aforementioned patents, namely, black level correction and white level correction. It has been found, however, that crosstalk occurs between adjacent photodiodes of this type.